This method is intended fordetermining the resistance of the colour of leather tothe action ofa standard artificial light source. The Xenonlamp has an emissionwavelength profile close to daylight.

 

In most (but not all) dye supplier’s pattern cards, the values reported are for dyeing on fullgrain chrome leather. It should be clearly understoodthat the light fastness rating obtained for dyed leather will changesignificantlydepending on the type of leather and amount of dye applied.

 

Method:

The side to be tested of the leather sample is exposed to light from a Xenon Lamp, under controlled conditions,along with eight blue dyed wool standards(blue scale).The light fastness is assessed by comparing the fading of the leather with the fading of the blue standards.The fading is typically made in 2 exposure times to better assist the evaluation.

The exposure time can be varied depending on the lamp intensity and the blue scale level required. To measure up to a maximum blue scale level 3 an exposure of 20h and 80h (as below) is often sufficient for a quickchecking of the light fastness rating.

Important:for measuring the light fastness in the blue scale 3 – blue scale 6 range, exposure times of 144h and 280h are necessary.